The Central California Blood Center needs additional help to offset a busy weekend that dropped the Valley’s blood supply to 39 percent.

The Blood Center is asking all blood donors to donate at centers in Visalia and Fresno in an effort to replenish the community’s supply.

Ongoing trauma and emergency room use up and down the Valley, and several weather-related accidents caused the demand for blood to spike, the Blood Center said. Trauma center patients used almost all the Valley supply of O-negative blood, which has now dropped below 9 percent.